test
<canvas height="100" width="250"></canvas>
test
<script type="text/javascript">
var canv = document.getElementsByTagName("canvas")[0],
	ctx = canv.getContext("2d");
ctx.fillStyle = "black";
ctx.fillRect(0, 0, canv.width, canv.height);
ctx.fillStyle = "red";
ctx.fillRect(10, 10, 230, 80);
</script>